Flora of the Canadian Arctic Archipelago
English: Short spike water milfoil,
French: Myriophyllum de sibérie.
Haloragaceae, Water-milfoil family.
Published in Feddes Repert. 13: 168. 1914.
Type: Russian Far East: Kamchatka River basin, leg. V.L. Komarove, selected by Aiken and Cronquist, Taxon 37: 959. 1988. Lectotype: LE.
Synonymy. Myriophyllum exalbescens Fernald, Rhodora 21: 120. 1919.
Myriophyllum. spicatum L. subsp. exalbescens (Fernald) E. Murray, Kalmia 12: 22. 1982.
Myriophyllum spicatum auct., non L., 1753.
Vegetative morphology. Plants 5–20 cm high (in arctic collections, commonly to 100 cm in southern Canada); perennial herbs (from persisting overwintering buds or "turions"); sometimes vegetatively proliferating by bulbils on stems or leaves (specialised overwintering turions), or sometimes vegetatively proliferating by fragmentation. Only fibrous roots present. Roots developed from free-floating fragments. Ground level or underground stems horizontal, or absent (plants grown from turions have a U-shaped base to the stem). Ground level or underground stems scales darker green, thicker, turnion leaves often remain at the base of the stem. Aerial stems erect. Leaves present; heterophyllous (often with smaller, thicker, dark green turion leaves at the base of the plant and larger, paler, thinner, green summer leaves); distributed along the stems; whorled; dying annually and non-persistent (summer leaves), or persistent (turion leaves persist for more than 12 months in Arctic specimens). Petioles 0.1–0.2 mm long. Leaf blades simple (divided). Leaf blade bases cuneate. Leaves not grass-like. Blades 10–25 mm long (in Arctic specimens, to 45 mm long in plants growing in southern Canada), 15–35 mm wide (Arctic specimens), spreading, ovate (broadly, in outline), flat. Blade adaxial surface glabrous. Blade abaxial surface glabrous. Blades cut into linear divisions (fewer than 14 on either side of the midvein). Blade margins deeply divided, glabrous. Hydathodes absent (on the leaves, present as dark pores on the stems).
Reproductive morphology. Flowering stems circular or oval in cross section. Flowering stems with leaves; rooting at the lower nodes (especially in soft mud). Inflorescences without bulbils (in the Arctic, plants sometimes form bulb-like turions without flowering); spicate; terminal; 3–10 cm long; 0.4–0.6 mm wide; elongating as the fruit matures. Inflorescences main axis glabrous. Pedicels absent. Bisexual spike(s) with empty bracts at the base (and bracteoles). Flowers small; radially symmetrical (actinomorphic); unisexual (female flowers basal usually, male flowers towards the top of the inflorescence, occasionally bisexual flowers occur in the middle of the spike). Sepals conventional (male flowers), or absent (female flowers); 4; free; 0.5–1.5 mm long; 0.5–1.5 mm wide; green, or pink; herbaceous (if applicable). Calyx glabrous. Petals conventional (male flowers), or absent (female flowers); free; 4; pink (if applicable); ovate; unlobed; 0.2–0.4 mm long; 0.1–0.2 mm wide (male flowers). Stamens 8. Anthers yellow; 1–1.2 mm long. Ovary inferior; carpels 4; syncarpous. Styles absent (pinkish fluffy, sessile stigmas on the top of each carpel). Placentation axile. Ovules per ovary 1 (per locule). Fruit sessile; dry; a schizocarp (splitting into 4 mericarps), or a mericarp; ovoid, or oblong; brown; 1–2 mm long; 0.8–1.1 mm wide; glabrous (with slight warts); not distinctly flattened; schizocarpous. Seeds 1 (per mericarp).
Chromosome information. 2n = 42.
2n = 42. Löve (1961, 1983, Iceland); Packer (1964, western Canada); Löve and Ritchie (1966, northern Canada); Aiken in Löve (1978b, North America); Löve and Löve (1982a, central Canada).
Ploidy levels recorded 6x.
Ecology and habitat. Substrates: tundra ponds; aquatic; calcareous. Shallow, calcareous streams.
North American distribution. Alaska, Yukon, continental Northwest Territories, Nunavut Islands, continental Nunavut, northern Quebec, Labrador. Range in the Canadian Arctic Archipelago limited. Rare. Low Arctic, boreal. Arctic islands: Baffin, Victoria, Southampton.
Northern hemisphere distribution. Circumpolar, or circumboreal. Northern Iceland, Northern Fennoscandian, KaninPechora, Polar Ural Novaya Zemlya, YamalGydan, Taimyr Severnaya Zemlya, YanaKolyma (?), West Chukotka, East Chukotka, West Alaska, North Alaska Yukon, Central Canada, Labrador Hudson Bay, West Greenland.
General notes. Porsild (1964) used the species name Myriophyllum exalbescens Fernald and reported a single collection from the west coast of Baffin Island as the only collection from the Arctic Archipelago. We are aware of four other collections since then.
Aiken and Cronquist (1988) explained why the name M. exalbescens falls into synonymy under M. sibiricum, which they lectotypified.
The first collections from the Arctic Archipelago reflected the short and cold growing season available for submerged aquatic plants. They were usually 10–15 cm tall, with evidence of the previous season's turions in a characteristically curved base to the plants associated with smaller, thicker, dark green leaves. Plants collected on Baffin Island, before the end of August, were already developing the next season's overwintering turions without having flowered. However, in 2001, flowering plants were found on Southampton Island. They were beginning to flower in early July, and were growing in a very shallow pond, and had experienced a period of weather with temperatures over 20°C for several days.
While definitive identification is difficult on vegetative specimens, the variation in the shape of overwintering turions and the transition between turion leaves and summer leaves in one sample suggests that M. verticillatum may also be present in the Arctic Archipelago (Aiken et al. 1979, Aiken and Waltz 1979).
Illustrations. • Plants in shallow pool. Mark Mallory, Canadian Wild Life Service, reaches into a bed of Myriophyllum sibiricum to insert a size marker. The marker tag is about 10 cm high, indicating that the water was very shallow. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting 01–067. CAN. • Close-up of flowering plants. Young flowering stem above water, and many developing flowering stems under water on the right- hand side of the image. The plants are covered with silt and dust. The lowest whorl on the flowering stem has blooming female flowers. The right-hand flower has four fluffy, pale yellow, sessile stigmas. The upper reddish whorls are female flowers in bud. Male flowers develop at the top of the inflorescence. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting 01–067. CAN. • Close-up of inflorescences. Spicate inflorescence with unisexual flowers. Female flowers at the base have a perianth. Male flowers at the apex have 8 stamens and no perianth. Ontario, Cape Henrietta Maria. CAN 152823. • Close-up of female flower. Female flower with bract and bracteoles. Each inferior ovary has a sessile, fluffy, pinkish stigma above 4 carpels. Ontario, Cape Henrietta Maria. CAN 152823. • Close-up of male flowers. Bracts and bracteoles occur at the base of the receptacle. Anthers arise at the top of the receptacle. Ontario, Cape Henrietta Maria. CAN 152823. • Winter buds near water surface. This photo of Myriophyllum verticillatum, not found in the Flora region, shows turions. Dark green specialised overwintering buds, turions develop near the surface of the water. These turions develop apically in our species Myriophyllum sibirium; compare with herbarium specimen in next picture. Pressed specimens suggest that in the arctic plants may go from turion to aquatic leaves back to turion formation without flowering in the short summers. Minnesota, Minneapolis 1978. Photograph by K. Waltz. • Herbarium specimen: Baffin Island. Vegetative only plants. Plants developing from turions have this characteristic U-shape at the base. Turions have short dark green leaves; summer leaves are longer, thinner, pinnately divided, and with more leaf divisions. Note turions (T) forming at the apices. Nunavut, Baffin Island, Nettilling Lake. CAN. • Arctic Island Distribution.
This publication is available on the internet (posted May 2011) and on CD-ROM (published in 2007). These versions are identical in content, except that the errata page for CD-ROM is accessible on the main index page of the web version.
Recommended citation for the web-based version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. NRC Research Press, National Research Council of Canada, Ottawa. http://nature.ca/aaflora/data, accessed on DATE.
Recommended citation for the CD-ROM version of this publication: Aiken, S.G., Dallwitz, M.J., Consaul, L.L., McJannet, C.L., Boles, R.L., Argus, G.W., Gillett, J.M., Scott, P.J., Elven, R., LeBlanc, M.C., Gillespie, L.J., Brysting, A.K., Solstad, H., and Harris, J.G. 2007. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. [CD-ROM] NRC Research Press, National Research Council of Canada, Ottawa..